Undetected Window

India cannot eradicate tuberculosis unless it treats the infection in cattle.

- Kundan Pandey

FOR A world free of tuberculosis, the World Health Organization has set a few targets: reduction of incidence rate by 90 per cent and deaths by 95 per cent by 2035 from the 2015 levels. To comply with the targets India—that accounts for 23 per cent of the global TB burden—has adopted newer strategies and tools. It is also coping with challenges like emergence of drug-resistant TB. It may still fall short of the targets because the strategies ignore a crucial factor—transmission of TB from animals, especially cattle.

Mycobacterium tuberculosis is a pathogen that primarily causes TB in humans. Occasionally people also get infected with M bovis, the primary pathogen of bovine TB. But this burden of zoonotic TB (transmitted from animals to humans) remains underestimated, says a review of studies published in The Lancet Infectious Diseases in September. Authors of the review call for a critical evaluation of zoonotic TB, especially in areas where TB is endemic and where people live in close proximity to infected animals or consume raw dairy products. Earlier in 2012, the International Livestock Research Institute had estimated that bovine TB could be responsible for up to 10 per cent of human TB cases.

These studies are alarming for India, which accounts for 52 per cent of the global cattle population and where cattle are an integral part of rural households. In the absence of a national agency to document the prevalence of bovine TB, let alone study its transmission to humans, existing research paints a disturbing picture.